The invention relates to a method for the recording and reproduction of video and/or audio signals in which an additional information item, in particular a title information item, is recorded in addition to the video and/or audio signal, which information item serves for subsequent insertion into the video picture during reproduction of the video signal and/or audio signal. The invention furthermore relates to a recording and reproduction apparatus for the recording and reproduction of video and/or audio signals in which the method for the recording and reproduction of video and/or audio signals is employed.
The invention relates to a method for the recording and reproduction of video signals. In this case, a method and an apparatus for magnetic recording and reproduction are disclosed in European Patent Specification EP 0 558 328. The apparatus described relates to an 8 mm video recorder. The apparatus affords the possibility of recording title data in addition to the video signal and the PCM audio data in a slanted track of the video tape. The title data, like the PCM audio data, are recorded digitally. In addition to the title data, it is possible to record control codes which determine the way in which the title data are presented. The separate storage of the title data makes it possible to afford the user a selection option which enables him to decide whether or not a title insertion is to take place.
From the development of DVD players, which have recently become commercially available, it is known to provide so-called sub-picture decoding devices for the display e.g. of subtitles on the screen of a television set. A description of such sub-picture decoding devices may also be found in the DVD Standard, DVD Specifications for read-only disc, part 3, video specification, Version 1.0, August 96, Section 5.4.3 Sub-picture Unit (SPU).
A more detailed description of such sub-picture decoding devices may also be found in EP-A-0 725 541, which also contains information regarding the encoding of sub-picture units (SPU) for the professional sector in the context of the production of DVD discs.
It is customary practice in many apparatuses appertaining to consumer electronics to insert status information items of the respective apparatus as well as operating instructions, etc., in the output video picture. Moreover, the use of so-called on-screen display menus (OSD) for operational control is widespread. It is customary nowadays for specialized microcontroller circuits with internal or external ROM and RAM memories to be used to generate such OSD menus or else status displays. These circuits are mainly designed such that the dot matrix-like pattern for each character that can be displayed is stored in the ROM memory. Characters that can be displayed should also include graphics characters with the aid of which, by way of example, appropriate bar charts can be composed. For an OSD menu, the requisite character codes are then transferred to a character generator which takes the associated dot matrix data from the ROM and generates the associated RGB signals at the correct locations in the picture and inserts them in the picture. The solution can also be configured for apparatuses with digital signal processing (including digital frame stores) in such a way that the pixel data are generated by the character generator and are written directly to the frame store at the corresponding locations. With regard to the DVD recording and reproduction apparatuses (DVD video recorder, DVD audio recorder, DVD camcorder) currently in development, the problem exists that, on the one hand, both the sub-picture decoding unit already mentioned must be implemented, with outlay on hardware, for the subtitles stored on the DVD disc and, on the other hand, additional title data are intended to be recorded for which a dedicated data pack has not been provided heretofore in the DVD Standard, with the result that, in the first instance, the only possibility remaining is for the title data to be integrated directly in the data packs for the video data, but this means that these title data are permanently connected with the video data and an option for selecting whether the title data are inserted into the video picture or are blanked out of the video picture no longer exists.
The object of the invention is to specify a method and an apparatus for the recording and reproduction of video and/or audio signals which make it possible, in particular for DVD recording and reproduction apparatuses, to separately store an additional information item, such as e.g. a title information item, in addition to the video and/or audio data, with the result that it becomes possible, without a high outlay on circuitry, to insert or blank the additional information item into or out of a video picture in a targeted manner. The object is achieved by means of the features of the claimed invention. The inventive solution in accordance with the present invention consists in converting the data for the additional information item into a sub-picture unit, which is recorded in at least one sub-picture data pack in addition to the data packs for the video and/or audio signal on the storage medium. This solution affords the advantage that it is not necessary to change the existing DVD Standard for the storage of additional information items, since the additional information items are converted into a sub-picture unit (SPU), which are already provided in any case in the Standard for DVD players. A further advantage is that a plurality of different additional information items can be recorded in this way without difficulty and, during reproduction, the user can select which of the additional information items he would like to have inserted, since even the existing DVD players already provide the option of selecting subtitles in different languages.
It is likewise advantageous that the outlay on circuitry at least for the reproduction of the additional information items is very low, since for this purpose use is made of the same sub-picture decoding unit which is also used otherwise during the decoding of the sub-picture unit for subtitles. An additional circuit can therefore be omitted in this case.
Advantageous developments and improvements of the present invention are specified in the claims. In particular, the fact that the sub-picture unit comprises a compressed bit map for the additional information items is defined by the present invention. This property is advantageous because a considerable amount of memory space can be saved as a result. The memory space obtained in this way can be used for concomitantly storing a plurality of different additional information items which can be inserted alternatively. Furthermore, the fact that a sub-picture unit comprises a table with control commands for the insertion representing the additional information item is defined in the present invention. Commands of this type are already known from the DVD Standard. They allow diverse possibilities for configuring the insertions. Thus, graphical symbols can also be inserted, and it is possible to use different types of highlighting for characters etc. Therefore, the additional information item is not just restricted purely to text information, it can also relate to specific symbols and graphics.
By way of example, in accordance with the present invention, run length coding can advantageously be used for the compression of the bit map. This is simple to implement.
According to the present invention, the additional information item can be input by an operator or else be machine-generated, such as e.g. in the case of insertion of the playing time or of the time of day and of the date.
A very advantageous measure is also specified, which prescribes the provision of a table with characters that are already run length-coded, from which table the characters required for the additional information items are selected and are combined to form the resultant bit map of the sub-picture unit. This considerably simplifies the routine coding process. The concrete specifications which are made in the table for each character are also specified. A number of different additional information items which can be recorded are also specified.
A programming option which enables the user to prescribe the order in which the additional information items that he desires are to be successively inserted can also advantageously be provided in the method according to the invention.
A corresponding recording and reproduction apparatus for the recording and reproduction of video and/or audio signals in which an additional information item can additionally be recorded is also specified.